I've been studying the schematic and have a few questions for those SD60 experts. I'm just looking at the first two gain stages:
1) the dual 500k pot. This brings both the first and second gain stages up in unison. I suppose two seperate pots would work as good or better. Is this a SD60 innovation or compromise?
2) I find the lack of input grid resistors interesting. It would seem to be good practice to add 10k resistors, or would I loose something?
3) What does the 560k, .001/ 220k, 420pf circuit do? Can't say I've seen this before.
thanks in advance
Couple of SD60 questions
Moderators: pompeiisneaks, Colossal
Re: Couple of SD60 questions
Sorry, I mean't to stick this on the other SD 60 thread. Well lets see what happens 
ps: That's SD as in Naylor Super Drive
ps: That's SD as in Naylor Super Drive
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Smokebreak
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Re: Couple of SD60 questions
I'm far from an expert, but
1. I think the idea is for a smoother "transition" into overdrive. Sure you can use 2, and may like that better. I find, these days, unless its a 4+ gain stage, 1 gain knob on the front panel is plenty. That's just me though. I'll end up wasting half a day looking for the "sweet spot" with 2 knobs.
But, having that 2nd pot in there(dual gang or otherwise), in 3 stage mode, is gonna make the amp more aggressive when cranked, as aMarshall would have a voltage divider and peaker . So its darker, ballsier. That's my theory.
2. Apparently it's always good to have stoppers unless it's an Express
Seriously, IIRC there are some shots with gridstops
3. Looks like a couple of treble peaking networks in series. The 560//1000p is standardish Marshall(470K//470p), but with frequencies down into the mids boosted as well. Fatter. The next one is similar but would have less treble peaking effect, I think. I'm not sure what the effect of having them both in series is.
1. I think the idea is for a smoother "transition" into overdrive. Sure you can use 2, and may like that better. I find, these days, unless its a 4+ gain stage, 1 gain knob on the front panel is plenty. That's just me though. I'll end up wasting half a day looking for the "sweet spot" with 2 knobs.
But, having that 2nd pot in there(dual gang or otherwise), in 3 stage mode, is gonna make the amp more aggressive when cranked, as aMarshall would have a voltage divider and peaker . So its darker, ballsier. That's my theory.
2. Apparently it's always good to have stoppers unless it's an Express
Seriously, IIRC there are some shots with gridstops
3. Looks like a couple of treble peaking networks in series. The 560//1000p is standardish Marshall(470K//470p), but with frequencies down into the mids boosted as well. Fatter. The next one is similar but would have less treble peaking effect, I think. I'm not sure what the effect of having them both in series is.